I still don't know whether term Content Delivery Network is commonly known so I can promote it directly of if it will better to promote website acceleration, video on demand solution or any other particular function.

Hardest part is to address specifically webmasters in need of such service. What are the best B2B online marketing methods in this field?

As per my personal view,CDN stands for Content Delivery Network. It is an interconnected system of computers on the Internet that provides a rapid web content to numerous users by duplicating the content on multiple servers and directing the content to users based on proximity.
The replication of the content is made through CDN and once the replication of the content has been made , it is delivered to users with greater speed and reliability.